A CCTV clip of the Mini passing Joules, the bar where Mr Regan had been, enabled PC Wood to take measurements and calculate its speed as 36mph, with a 10% margin of error meaning the speed could have been 3.6mph less or more.

Another calculation, the Searles equation, can be used to measure a vehicle's speed as it hits a pedestrian.

PC Wood said this could not be accurately used as the impact was only a "glancing blow" but said it gave him a range of speeds from 33mph to 40mph.

Ben Regan in full military dress

Polmeer admitted in his first police interview he knew the speed limit in Bell Street was 30mph but that he estimated he was going between 30mph and 40mph.

PC Wood also told the court Mr Regan was wearing dark jeans and a t-shirt and that light from the nearest street lamp was obscured by trees, reducing visibility.

PC Wood measured the impact area by looking at the debris in the road - including paint flakes, glass, Mr Regan's shoes, and a scuff mark on the kerb.

The officer believed Polmeer's car was not travelling normally in its lane.

PC Wood said: "I'm happy to say the vehicle was either straddling the white line or over the white line."

Ben Regan with his dad Jim after his passing out ceremony

Crossing the road, Mr Regan reached 4.6 metres from the edge of the cars parked along the road, which would have taken him 2.3 seconds at walking speed, 1.1 seconds at jogging speed or somewhere in between for a fast walk.

And reaction time for an unexpected event during nighttime would be two to three seconds, PC Wood said.

It was also disputed whether Mr Regan was on his phone at the time of the collision.

The court heard a 33 second call was made from his phone at 1.57am.

Ben Regan

An imprint was also made on the car which consistent with Mr Regan's arm being up to his ear, Simon Stirling, defending, said.

Mr Regan's post-mortem showed he sustained a broken right arm.

Mr Stirling described the collision. "Striking Mr Regan on his legs and then as a result of him going into the windscreen and the impression made with the arm and the impact causing damage to the windscreen and the roof," he said.

Imagining the scenario to explain the scuff marks on the kerb, Mr Stirling later added: "Straddling the white line, the pedestrian steps out in front of the vehicle. It swerves travelling at 30 to 40mph, strikes the kerb and comes back into the line and drives off without applying the brakes."